Sanyo microwave EMS667W, diff high power ratings

Question

I put a frozen dinner in and pushed Froz dinner, but after cooking it was still frozen. I then put dinner back in for 5 min and it was still frozen. Obviously the power strength was wrong, but I cannot work out how to ensure I have 100% power. Pushing power and 10 as book says only sets time for 10 secs.

Or is there a fault in this new oven and should I return it?

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